Think Cheshire Cat of Alice's adventures in wonderland.

Edit to include a quote I found on this character, I'd say its a great description.

" The Cat’s Grin: One cannot discuss the symbolism of the Cheshire Cat without mentioning its enigmatic grin. The cat’s smile represents a sense of ambiguity and mystery, reflecting the unpredictable nature of Wonderland itself. This grin serves as a reminder that appearances can be deceiving, emphasizing the importance of looking beyond the surface to uncover the truth."

Think Cheshire Cat of Alice's adventures in wonderland.